1. Field of the Invention
The present invention relates to an ink cartridge suitable for an ink jet printer, and particularly to an ink cartridge having a pressure regulator with an elastic member therein, thereby to allow air enter the ink tank and prevents ink or air exit from the ink tank.
2. Description of the Prior Art
In the conventional ink jet printer, the ink is loaded in an ink cartridge for supplying the ink to an ink delivery needle of the ink jet printer due to print paper. Referring to FIG. 1, the ink cartridge generally comprises an ink tank having an ink tank body la or a plurality of ink tank bodies for loading different color ink, wherein the ink tank body 1a is sealed with a cover lid 2a thereon. The cover lid 2a has an ink filling inlet 20a and an ambient air vent 21a and a sealing film 22a is attached on a top surface of the cover lid 2a so as to seal the ambient air vent 21a and the filling inlet 20a. The ink tank body la has a bottom surface disposed with an ink outlet part 10a, and an accommodated chamber thereof positioned with an ink porous member 3a therein. A filter 11a is affixed to the inner end of the ink tank. Furthermore, firstly to remove the sealing film 22a, then to mount the ink cartridge into the ink jet printer, and the ink in fluid communication through the ink outlet part 10a of the ink tank body 1a to the ink delivery needle 6a of the ink jet printer. In the conventional ink cartridge, the top surface of the cover lid 2a is formed with a circuitous channel 23a (shown in FIG.2) that is extended with a long distance channel due to the ambient air vent 21a for ventilation. Additionally, the ink tank must be ventilated in order to equalize pressure differences for the printer to work properly, however, the ventilation of the ink cartridge often results in some of the ink evaporating during use or unused condition, especially if the ink cartridge is used infrequently.
The porous member 3a in the ink tank acts as a wick, so that the porous member 3a absorbs all ink and wick ink towards the ink delivery needle 6a. The filter 11a is provided for filtrating some parts departed from the porous member 3a to prevent some material of the porous member 3a obstructed the ink outlet part 10a or the ink delivery needle 6a. 
Therefore, the conventional ink cartridge has some disadvantages what follows:
1. The cover lid 2a has a complex top surface due to the circuitous channel 23a. 
2. The ink in the ink cartridge is evaporated easily due to the ambient air vent 21a. 
3. The porous member 3a absorbs much ink that will hold up therein and could not be used.
4. If the cartridge is recycled for using again, the porous member 3a must be discarded, and clean the ink tank body la and the filter 11a, so that it will pollute the environment.
The primary purpose of the present invention is to provide an ink cartridge which can provide a pressure regulator with an elastic member therein for unidirectional ventilation by a pressure difference between inside and outside, no air inlet hole is required, whereby the ink in an ink tank can be efficiently flowed out through an ink outlet part to an ink delivery needle of the ink jet printer and will not leak out.
Another purpose of the present invention is to provide an ink cartridge that does not require a porous member to hold up the ink, therefore tremendous reduction on production cost and also reduce the waste of ink which is already absorbed by the porous member.
Moreover, it is an environmental friendly user in term of recycling the ink cartridge, no cleaning process is required and certainly don""t have to worry about the used porous member and unused ink will pollute the environment. It just needs to simply fill in the ink through the ink filling hole.
In accordance with one aspect of the present invention, an ink cartridge comprising a hollow ink tank body defining an accommodating chamber therein, the ink tank body has an ink outlet port and a mounted seat being formed on a bottom surface thereof. A cover member having an ink filling inlet formed therein, the cover member being fixedly secured to said hollow ink tank body and sealing said accommodating chamber of said hollow ink tank body. A pressure regulator is mounted on the mounted seat and comprising a box body, an elastic member, and a cover body.
As a result of a negative pressure will increase during printing, the elastic member will change its shape and allow air pass through it unidirectional, and because the elastic member has a elastic force, the ink tank still maintains a certain amount of negative pressure and thereof the ink will not leak through the pressure regulator to outside.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. Other advantages and features of the invention will be apparent from the following description, drawings and claims.